NPC Inverter Research Articles

Improved Switching Technique to Mitigate THD and Power Loss of NPC Inverters

Improved Switching Technique to Mitigate THD and Power Loss of NPC Inverters

Discontinuous Pulse Width Modulation Strategy for Single-phase Five-level T-type NPC Inverter considering Symmetric Thermal Loadings of Power Devices

Discontinuous Pulse Width Modulation Strategy for Single-phase Five-level T-type NPC Inverter considering Symmetric Thermal Loadings of Power Devices

Sensorless DTC Based on Artificial Neural Network for Independent Control of Dual 5-Phase Induction Machine Fed by a Three-Level NPC Inverter

Sensorless DTC Based on Artificial Neural Network for Independent Control of Dual 5-Phase Induction Machine Fed by a Three-Level NPC Inverter

A carrier pulse width modulation for asymmetric three-level NPC inverter

A carrier pulse width modulation for asymmetric three-level NPC inverter

Hybridized PWM Strategy for Three- and Multiphase Three-Level NPC Inverters

Hybridized PWM Strategy for Three- and Multiphase Three-Level NPC Inverters

A highly effective and simplified DPWM algorithm for NPC inverters for high power factor load applications

A highly effective and simplified DPWM algorithm for NPC inverters for high power factor load applications

Optimizing Power Quality in Distribution Systems: A Three-Phase Three-Level Shunt Hybrid Active Filter with Multilevel Inverter Approach

This paper presents an advanced solution for improving power quality in distribution systems through the implementation of a Three-Phase Three-Level Shunt Hybrid Active Filter (SHAF) with a Multilevel Inverter. The SHAF, utilizing a Three-Level Neutral Point Clamped Voltage Source Inverter actively mitigates harmonics, with a comprehensive performance analysis considering the impact of active and passive parameters on power quality improvement. The proposed system incorporates TPTL (Three phase 3-Level) NPC inverter technology to reduce switch ratings and enhance harmonic compensation. Various passive filters are integrated into the SHAF to assess performance. Simulation results, validated with MATLAB/Simulink, confirm the efficacy of the proposed system. Comparative analysis against conventional shunt passive filters, including Single Tuned, Double Tuned, High Pass, C-type High Pass, and a two-level shunt active filter with diverse passive filters, reveals a significant improvement of over 53% compared to two-level active filters and more than 16 times compared to shunt passive filters.

A reduced vector model predictive controller for a three-level neutral point clamped inverter with common-mode voltage suppression

This paper presents a novel, state-of-the-art predictive control architecture that addresses the computational complexity and limitations of conventional predictive control methodologies while enhancing the performance efficacy of predictive control techniques applied to three-level voltage source converters (NPC inverters). This framework's main goal is to decrease the number of filtered voltage lifespan vectors in each sector, which will increase the overall efficiency of the control system and allow for common mode voltage reduction in three-level voltage source converters. Two particular tactics are described in order to accomplish this. First, a statistical approach is presented for the proactive detection of potential voltage vectors, with an emphasis on selecting and including the vectors that are most frequently used. This method lowers the computational load by limiting the search space needed to find the best voltage vectors. Then, using statistical analysis, a plan is presented to split the sectors into two separate parts, so greatly limiting the number of voltage vectors. The goal of this improved predictive control methodology is to reduce computing demands and mitigate common mode voltage. The suggested strategy's resilience is confirmed in a range of operational scenarios using simulations and empirical evaluation. The findings indicate a pronounced enhancement in computational efficiency and a notable diminution in common mode voltage, thereby underscoring the efficacy of the proposed methodology. This increases their ability to incorporate renewable energy sources into the electrical grid.

ADRC-LSE Control of a Dual-Star Induction Motor Powered by a Dual 3-level NPC Inverter

In the context of electric vehicle propulsion drives, this paper presents anActive disturbances Rejection Control (ADRC) strategyapplied to a Dual Star Induction Motor (DSIM)powered by dual 3 levels inverter type NPC. The proposed method focuses on enhancing the Active Disturbance Rejection Control (ADRC) method by integrating Least Squares Estimation, establishing a direct relationship between the control law and the necessary frequency for the DSIM to turn in the exact speed whatever the load torque applied. The ADRC with Least Squares Estimation is compared with Field-Oriented Control (FOC) to evaluate their performance in tracking reference speed and stabilizing time. Additionally, another test is conducted to assess the ADRC's ability to reject disturbances. Results from the simulation demonstrate the effectiveness of ADRC with Least Squares Estimation, showcasing its potential for optimizing DSIM control in electric vehicle applications, thereby contributing to enhanced efficiency and stability.

Circulating currents control method for paralleled three-level NPC inverters

Circulating currents control method for paralleled three-level NPC inverters

Non-Weighted Two-Stage Model Predictive Control Strategy Based on Three-Level NPC Inverter

This paper investigates the asynchronous motors driven by a Three-Level Neutral-Point-Clamped Voltage Source Inverter (3L-NPC-VSI) and aims to achieve control without weight factors and reduce torque ripple. It puts forward a non-weighted two-stage Finite-Control-Set Model Predictive Control (FCS-MPC) strategy. First, a hierarchical optimization method is adopted to address the difficulty of setting weight factors in traditional FCS-MPC applications. The method offers stratified designs of three performance indices, voltage jump, common-mode voltage, and current tracking, obviating the need for weight factor setting and reducing the calculation load of predictions. Secondly, to further mitigate torque ripple, an optimal vector or vector combination is implemented at the current control layer by adhering to the principle of minimal current tracking error. During the selection of the optimal vector combination, the first vector of the combination is chosen to be the vector at the end of the present cycle. This ensures that there is at most one switch within each control period, reducing the switching losses of the two-stage FCS-MPC. Lastly, detailed simulation and experimental analyses are conducted to verify the feasibility and effectiveness of the proposed strategy.

Discontinuous PWM Strategy for Reliability and Efficiency Improvements of Single-Phase Five-Level T-Type Inverter

Reliability and efficiency improvements of PV inverters have a high potential to decrease the cost of PV energy. Discontinuous PWM is an effective method to improve both the efficiency and reliability of the power devices of the single-phase five-level T-type NPC inverter. However, applying DPWM gives a negative effect on the lifetime of the DC-link capacitors and thus reduces the reliability of the inverter from the system-level reliability point of view. This paper proposes the DPWM strategy to improve the lifetime of the DC-link capacitor compared with the conventional DPWM method so that both the reliability and efficiency of the single-phase five-level T-type NPC inverter are improved. Through the proposed strategy, the lifetime of the DC-link capacitor is improved, but its negative effects on the efficiency of the inverter and the lifetime of the power devices are negligible. Therefore, the advantages of applying DPWM can be sustained. Simulation and experimental results verify the feasibility and effectiveness of the proposed DPWM strategy.

On the Design and Analysis of a Weighting Factor Free-Based Predictive Flux Control Strategy for Three-Level NPC Inverter-Fed IM Drives

On the Design and Analysis of a Weighting Factor Free-Based Predictive Flux Control Strategy for Three-Level NPC Inverter-Fed IM Drives

Open Circuit Fault Localization in NPC Inverter Fed Induction Motor Drives Using Cost Function and Estimated Voltages

Open Circuit Fault Localization in NPC Inverter Fed Induction Motor Drives Using Cost Function and Estimated Voltages

A three phase 3-level inverter with reduced THD factor

The paper presents an mathematical analysis of a stepped function denoted as fN=6 . This function describes precisely an output voltage waveform of a 3-level inverter. The analysis proves that cascaded inverters give a very good performance of the output voltage according to a criterion of minimal THD. Optimal parameters are indicated in the paper. They permit to diminish the THD factor to a level below 21% while in standard NPC inverters such a result requires special treatment.

Efficiency Analysis of Single-Phase Photovoltaic Transformer-less Inverters

This paper presents an efficiency analysis of five single-phase transformer-less inverters for photovoltaic applications (Full H-Bridge, Half H-Bridge, H5, HERIC and NPC inverters) implemented with different topologies of switches. Silicon (Si) and Silicon Carbide (SiC) diodes have been considered combined with two kinds of IGBTs. Simulation results have been obtained for each of the systems in different operating conditions by using PLECS software. Power losses and European Efficiency (EE) have been calculated for all the topologies by including the real characteristics of the switches in the thermal models provided by the software

Simple Design Scheme for a 300 kW Modular NPC Inverter Using Thermal RC Network Analysis

This paper proposes a simple design scheme for a modular NPC inverter using thermal RC network analysis. The proposed design process is an efficient and straightforward approach to designing the heatsink for a 300 kW modular neutral-point-clamped inverter. The heatsink design plays a crucial role in achieving high power density of a power converter because the weight and size of the heatsink are primarily influenced by its type. The structure and dimensions of the heatsink are mainly determined based on the generated heat by losses of the power semiconductor switches. In this paper, a thermal RC network model was established using parameters from the power switch module and was applied to the simulation of the power converter. The thermal losses of the power semiconductor switches were calculated via this process, and the heatsink was designed according to the calculated thermal losses. The proposed design scheme was analyzed and compared with the thermal fluid dynamic model. To validate the feasibility of the proposed design process, The simulation results were compared with experimental results.

Research on topology of a novel three-phase four-leg fault-tolerant NPC inverter

Research on topology of a novel three-phase four-leg fault-tolerant NPC inverter

Measurement and intermittent performance analysis of 12-switch NPC inverter driven PMSM drive in electric vehicle application

Measurement and intermittent performance analysis of 12-switch NPC inverter driven PMSM drive in electric vehicle application

Sensorless integral backstepping control of a single-stage photovoltaic system connected to the single-phase grid using a multi-level NPC inverter with an LCL filter

In this paper, the control problem of a single-phase, grid-tied photovoltaic (PV) system consisting of a three-level neutral point clamped (3L-NPC) inverter and an LCL filter is considered. The proposed controller aims at achieving threefold control objectives: (i) guaranteeing the PF correction (PFC) objective by enforcing the current of the grid to track a sinusoidal reference signal in phase with the grid voltage; (ii) controlling the DC bus capacitor voltages to follow a reference value provided by the maximum power point tracking (MPPT) algorithm to achieve the maximum available PV power; (iii) ensuring a balanced power exchange through the regulation of the two input capacitor voltages to the same values. To achieve these aims, a multi-loop nonlinear controller is synthesized, including three control loops, specifically the inner PFC requirement loop designed through the integral backstepping approach, the outer voltage control loop formulated using a filtered proportional integral (PI) regulator, and the power balance loop built up using a PI regulator. The control problem under consideration entails several difficulties as the existence of numerous state variables that are inaccessible to measurements. This challenge is addressed by adding a high-gain observer to estimate the current of the solar panels. The performance of the proposed controller against climate changes is demonstrated via numerical simulations using the MATLAB/Simulink platform.